How to run source bash command between two lines and from file

When i ran my start ADSL connection script, i've been many times blocked by a lock somewhere.
It's no matter, so i realized a python script that can do what the bash command "source" does, even this few line of python can gives you possibility to run codes given between two lines.
Here is the code :
#!/usr/bin/env python
import sys, os
if len(sys.argv) != 4:
print "Usage: source file startline endline"
sys.exit(1)
file = sys.argv[1]
start = int(sys.argv[2])
end = int(sys.argv[3])
fd=open(file, 'r')
data=fd.readlines()
enter = '\n'
for item in data:
if enter in data:
data.remove(enter)
for cmd in data[start-1:end]:
# debug print "exec command:", cmd.strip()
os.popen(cmd.strip())